ru.fix.stdlib.files.FileWatcher.kt Maven / Gradle / Ivy
package ru.fix.stdlib.files
import mu.KotlinLogging
import java.nio.file.*
import java.util.concurrent.Executors
import java.util.concurrent.TimeUnit
private val logger = KotlinLogging.logger{}
/**
* @param filePaths List of file paths to listen
*/
class FileWatcher : AutoCloseable {
private val watchThread = Executors.newSingleThreadExecutor { runnable ->
Thread(runnable, FileWatcher::class.java.name)
}
val dirToKey = mutableMapOf()
val keyToDir = mutableMapOf()
val keyToFileNameListeners = mutableMapOf Unit>>()
val watchService = FileSystems.getDefault().newWatchService()
fun register(filePath: Path, listener: (Path) -> Unit) {
val absoluteFilePath = filePath.toAbsolutePath()
val dir = absoluteFilePath.parent
if (!dirToKey.contains(dir)) {
val key = dir.register(watchService, StandardWatchEventKinds.ENTRY_MODIFY)
dirToKey[dir] = key
keyToDir[key] = dir
}
keyToFileNameListeners
.computeIfAbsent(dirToKey.getValue(dir)) { HashMap() }
.put(absoluteFilePath.fileName, listener)
}
fun unregister(filePath: Path) {
val absoluteFilePath = filePath.toAbsolutePath()
val dir = absoluteFilePath.parent
val key = dirToKey[dir] ?: return
keyToFileNameListeners.compute(key) { _, fileNameListeners ->
requireNotNull(fileNameListeners)
fileNameListeners.remove(absoluteFilePath.fileName)
if (fileNameListeners.isNotEmpty()) {
fileNameListeners
} else {
//last file name for the directory
dirToKey.remove(dir)
key.cancel()
null
}
}
}
init {
watchThread.submit {
try {
while (!Thread.currentThread().isInterrupted) {
val watchKey = watchService.take() ?: continue
val fileNameListeners = keyToFileNameListeners[watchKey] ?: continue
for (event in watchKey.pollEvents()) {
if (event.kind() == StandardWatchEventKinds.ENTRY_MODIFY) {
val fileName = event.context() as? Path ?: continue
val listener = fileNameListeners[fileName] ?: continue
logger.info { "Detect modification for: $fileName" }
try {
listener.invoke(keyToDir.getValue(watchKey).resolve(fileName))
} catch (interrupted: InterruptedException) {
throw interrupted
} catch (exc: Exception) {
logger.error("Failed to invoke listener of file change: $fileName", exc)
}
}
}
watchKey.reset()
}
} catch (closed: ClosedWatchServiceException) {
//stop processing
} catch (interrupted: InterruptedException) {
//stop processing
} catch (exc: Exception) {
logger.error(exc) { "Failed to watch for file changes" }
}
}
}
override fun close() {
watchService.close()
watchThread.shutdown()
if (!watchThread.awaitTermination(1, TimeUnit.MINUTES)) {
logger.error("Failed to await watch service close")
}
watchThread.shutdownNow()
if (!watchThread.awaitTermination(1, TimeUnit.MINUTES)) {
logger.error("Failed to await termination of watcher thread")
}
}
}